POLLEN INCOMPATIBILITY AND FRUIT SET IN LOWBUSH BLUEBERRIES

Abstract

Twenty-one clones of Vaccinium angustifolium were examined for self-fertility: 12 were completely self-sterile and 9 were partially self-fertile. It was concluded that the level of self-fertility in V. angustifolium is very similar to that in high-bush blueberry. Seed number in blueberry is significantly correlated with berry weight and with the time required for ripening. More seeds are associated with heavier berries and earlier ripening. Following pollination by Vaccinium myrtilloides, ovules of V. angustifolium de-veloped normally until the endosperm was partially developed. The ovules then aborted and the berries dropped. It is considered that the abortive ovules described as occurring normally in the development of V. angustifolium seeds may have been caused by those ovules being Fertilized by pollen of V. myrtilloides. When a mixture of V. angustifolium and V. myrtilloides pollen was used to pollinate V. angustifolium flowers, the percentage set was reduced and the resulting berries were smaller, contained fewer seeds, and were later ripening than the controls. These findings suggest that, other factors being equal, the yield of fruit from fields containing both V. angustifolium and V. myrtilloides will be less than from fields containing V. angustifolium alone, due to cross-pollination between the 2 species.